Viviana Gradinaru, Caltech With the advent of technologies such as CRISPR/Cas9, genome engineering for both basic research and therapeutic applications is becoming reality. An outstanding challenge is the mean to safely and efficiently transfer large genomes to desired cells across life span. We have developed an in vivo Cre-based selection platform (CREATE) for identifying adeno-associated viruses (AAVs) that efficiently transduce genetically defined populations. We used CREATE to select for viruses that transduce the brain after intravascular delivery and found a vector that nonspecifically transduces most cells across the adult brain. Since the restrictive nature of the blood brain barrier presents a major impediment toward treating CNS disorders our discovery has the potential to enable exciting advances in gene editing/replacement via CRISPR-Cas or RNA interference to restore diseased CNS circuits if the needed level of efficiency and specificity can be engineered for diseased targets. We plan to enable such efforts by creating viral-based solutions to non-invasive whole- brain large cargo delivery across the blood-brain barrier from embryo to adult by: 1. Generating AAVs for cell-type and region specific gene delivery across the blood-brain- barrier, noninvasively via the bloodstream in the adult rodent for neurodegeneration applications. 2. Generate AAVs capable of transducing the developing brain in utero with a simple systemic injection to the pregnant dam for neurodevelopment research and therapy. 3. Increase the packaging capability of AAVs by about 2-fold to enable delivery of large genomes for gene therapy and research. 4. Enable non-invasive circuit specific deep brain modulation by the use of systemic vectors and genetically encoded activity modulators (e.g. by chemogenetics or others in development now). Longer term we plan, in our laboratory and also with collaborators, to contribute our neurotechnologies (including, in addition to viral vectors, tissue clearing and optogenetic control and imaging) towards elucidating maladaptive neural circuits that contribute to brain pathology in neurodegeneration and neurodevelopment.
Significant advances have been made in genetic tools for anatomical and functional assessment of the brain and also in genome editing tools with potential to repair diseased circuits. The main barrier to deploying such tools to the developing and aging brain is the lack of non-invasive but highly specific modalities for gene delivery. We will engineer vectors that, when delivered to the bloodstream, can cross anatomical barriers (such as the blood-brain or placenta) and deliver useful cargo with high specificity to the brain across life stages.
